The role of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in local staging and breast lesion characterization is well established .
Compared with 1.5-T MRI, 3.0-T imaging allows higher signal-to-noise ratio, improved spatial resolution, and faster scanning and therefore may be able to test advanced added techniques as DTI to help in predicting the malignancy of lesions more accurately .
Based on the fact that DTI is a diffusion imaging applied in different directions, in trial to assess the diagnostic role of DTI, we compared it to DWI as a well-established diffusion parameter known for its good sensitivity and specificity in characterization of breast lesions and currently is an integral part of DCE-MRI breast.
This study included 50 patients presented with breast lesion, 31 malignant cases and 19 benign cases; their age ranged from 25 to 70 years, the most common age group (45–65 years) about 48% of the cases.
Seven cases aged 25 to < 40 years were included in this MRI study. Although they were classified by ultrasound as BIRADS 1, 2, or 3, they were assessed by MRI for clinical purposes to detect any suspicious lesion in symptomatic patients with BIRADS 1 or 2, especially in dense breast parenchyma or positive family history and to add MRI assessment for BIRADS 3 lesions, as well as for research purpose aiming to include benign lesions for testing DTI in addition to the malignant lesions.
As a result, the study included good spectrum of benign lesions as fibroadenosis, fibroadenomas, duct papillomatosis, granulomatous mastitis, and lymphocytic mastitis in addition to different pathological subtypes of malignant lesions as DCIS, IDC, invasive lobular carcinoma, Paget’s disease of the nipple, and mucinous carcinoma.
Although usage of DWI as a part of CE-MRI breast has been established with low ADC value as a feature of breast malignancy, there are contradicting results regarding the added value of DTI in differentiating between malignant and benign lesions. FA is the most studied DTI parameter. Some studies have reported higher FA in malignant lesions compared with benign ones as Teruel et al. , Baltzer et al. , and Tsougos et al. , while others like Partridge et al. , Eyal et al. , and Cakir et al.  have found no significant difference.
Our first concern was to optimize the DTI sequence to obtain good quality images for accurate reading of FA values.
For this aim, DTI sequence in our study was tested in a 3-T MRI machine which has been shown in prior studies improved diagnostic performance compared to 1.5-T due to superior signal-to-noise ratio (SNR) and increased spatial resolution .
Also, most of the published previous studies were testing DTI in breast imaging using a 1.5-T MRI machine (for example [4, 26]), so it was beneficial to provide some data about DTI in 3-T MRI.
Regarding the DTI sequence, medium number of gradient diffusion directions was chosen to ensure good quality of the sequence and at same time accepted acquisition time for the sequence. In addition, the DTI sequence was taken before contrast administration which may be preferable to avoid any possible confounding effect of the contrast on DTI parameters.
While comparing the DTI to DWI in our study, the DTI achieved lower sensitivity and specificity than DWI, it showed about 81% sensitivity and 51.7% specificity with cut-off value of FA to differentiation between malignant and benign lesions (0.2), compared to 90% sensitivity and 63% specificity of DWI. This is similar to results of a study, Baltzer et al. , which was carried on 59 patients to test diffusion tensor imaging of 1.5-T MRI breast revealed sensitivity 79.6% and specificity 64.7% with cut-off value of FA (0.19).
Jiang et al.  studied 88 patients with 88 breast lesions who underwent DTI on 1.5-T MRI reported cut-off values of ADC and FA for malignant breast lesions (1 ± 0.33 × 10−3 mm2/s and 0.2 ± 0.05), respectively, similar to the cut-off values in our study (1 × 10−3 mm2/s and 0.2), respectively.
Although DWI showed better overall sensitivity and specificity than DTI, DTI showed conclusive results in cases with DCIS, in which the DWI showed false positive or false negative results. This may indicate that FA can be more sensitive to changes in the microstructure of the cells before increasing cellularity of the lesion.
On the other hand, unlike our study, Cakrik et al. ,while examining DWI and DTI in 55 breast lesions (30 malignant, 25 benign) using 3-T MRI, concluded that ADC of DWI was discriminative for benign and malignant breast lesions while FA measurement was not. These controversies are encouraging for more investigations about optimization of DTI and testing its added value in MRI breast imaging.
Also, it was noticed that FA expressed better results in malignant lesions rather than benign lesions. This can be attributed to larger number of included patients older than 40 years old with higher number of malignant lesions than younger patients with benign tumors. Further studies with more number of benign lesions are advised to ensure that there is no bias in our analysis due to age factor.
There were some limitations in our study; the study was carried on a relatively small number of patients; however, a statistically significant difference was found suggesting that further prospective studies with a larger number of cases would be beneficial.
Detailed lesion assessment in DTI was limited by technical issues related to the single-shot echo-planar imaging (EPI) technique due to its limited spatial resolution and its frequent artifacts. The results of recent multicenter breast DWI trials stated that about 13 to 29% of cases are being excluded for DWI technical issues [27,28,29].
Also, the DTI sequence was time-consuming (the sequence time for 15 directions was about 10 min) with subsequent prolonged time of the whole MRI study to about 25–35 min. This time was not tolerated by all patients especially obese or asthmatic patients.
As a final limitation, ROIs were manually defined on DTI maps for each exam after comparing DCE-MRI and DTI. Manual ROI is prone to operator dependence and sampling error, especially for irregularly shaped masses or non-mass enhancement.